# 创建媒体缓存对象
class MediaCache:
    def __init__(self):
        self._cache = {}
        
    def add(self, media_id: str, file_path: str):
        self._cache[media_id] = file_path
        
    def get(self, media_id: str) -> str:
        return self._cache.get(media_id)
        
    def cleanup_expired(self):
        # 实现清理过期缓存的逻辑
        pass

# 创建全局缓存实例
media_cache = MediaCache() 